Lecithin is commonly added to cooking fats as an anti-sticking agent, but has the disadvantage that it darkens in color at high temperatures, thereby limiting the level which can be used. Foodservice establishments are often required to hold a heated fat for extended periods of time. Fats containing a higher than normal level of lecithin to enhance the anti-sticking properties darken more quickly when subjected to continuous heating. Associated with this discoloration is generation of an off-flavor. The increased darkening and generation of off-flavor render such fats unacceptable. An effective means of preventing the darkening of lecithin at high temperatures is desirable and would permit its use at increased levels in fats to improve their anti-sticking performance.
Fat or oil additives known for inhibiting darkening of phospholipids, such as lecithin, upon heating are primarily acidic or weakly basic compounds such as amino acid salts, carboxylic acids and derivatives, or salts of carbonates or bicarbonates. Inhibition of discoloration of phospholipids in fatty oils during heating can be achieved by the addition to the oil of a mixture of an acidic amino acid salt and a basic amino acid salt chosen from salts of arginine and glutamic acid, lysine and glutamic acid, or lysine and aspartic acid. In addition, sodium glutaminate, acetic anhydride or alkali metal acetate can be employed.
Restraint of phospholipid coloration upon heating also results from the addition of sodium succinate, or succinic acid to the fat. Japan Pat. No. 127,907, issued Oct. 4, 1979, discloses a vegetable cooking oil composition containing succinic acid or sodium succinate to prevent browning of phosphatides and spattering upon heating at greater than 150.degree. C. (302.degree. F.) The oil is prepared by adding to the base oil a minimum of 0.5% by weight phosphatide, a minimum of 1% by weight succinic acid or sodium succinate, and an optional oleophilic surfactant. After heating and stirring, insolubles are removed by filtration and more vegetable oil is added to adjust the phosphatide concentration to 0.5 to 5% by weight. The effects of the additives or the filtration on the anti-sticking properties of the fat are not disclosed.
Carbon dioxide-generating compounds also inhibit thermal darkening of fats containing phospholipids. Japan Pat. No. 110,210 of Matsueda et al., issued Aug. 29, 1979, discloses a barbecue oil composition containing vegetable oil, a phosphatide, and a compound that generates carbon dioxide upon heating. The latter inhibits spattering and coloration upon heating of the barbecue composition. The carbon dioxide-generating compound comprises the carbonates of potassium, ammonia, and magnesium, and bicarbonates of ammonia and sodium, added to the fat and lecithin mixture at a minimum level of 5% by weight, preferably 20% by weight, of the phospholipid. The oil is prepared by adding the carbon dioxide-generating compound to a 10% by weight solution of phosphatide in oil, heating to greater than 80.degree. C. (176.degree. F.), filtering, and dissolving in the vegetable oil. The anti-sticking properties of the oil composition are not discussed.
Pretreatment of lecithin to prevent thermal browning in heated fat compositions is taught by Japan Pat. No. 54,400, issued Apr. 21, 1980. The pretreatment comprises heating the lecithin in an inert atmosphere, either alone or diluted with a fat, at 150.degree. C. to 230.degree. C. (302.degree. F. to 446.degree. F.) for five minutes to one hour.
It has now been found that lecithin which has been pretreated in a small amount of fat with water and filtration resists excessive thermal darkening in heated fat compositions. Excessive discoloration of fats containing the filtrate when heated is decreased because much of the lecithin is removed by the filtration step. Surprisingly, the anti-sticking properties of a fat containing the filtrate are not substantially reduced compared to those of a fat containing untreated lecithin. Due to the reduction in thermal darkening, higher levels of pretreated lecithin can be employed to overcome any minor decrease in anti-sticking properties and provide fat compositions with improved anti-sticking effectiveness. Therefore, use of the organic acids, salt additives, or carbonate compounds of the Japanese patents can be avoided. Any adverse effect these may have on the taste or storage stability of the fat are prevented as well as any negative connotations associated with listing additives such as these on the label of a treated fat product.
Accordingly, it is an object of this invention to provide novel fat compositions which resist thermal darkening.
It is a further object of this invention to provide novel fat compositions with improved anti-sticking properties.
it is a further object of this invention to provide a process for the pretreatment of lecithin that will aid in decreasing its thermal discoloration in heated fats without substantially impairing its anti-sticking properties.
It is a further object of this invention to provide a process for the pretreatment of lecithin that will permit its use at increased levels in grilling fats to improve their anti-sticking effectiveness.
These and other objects of the invention will be evident from the following disclosure. All percentages are by weight unless otherwise indicated.